Pathogenic Escherichia coli (E. coli) bacteria are one of the most dangerous agents of food-borne disease. Consumption of contaminated food or water can be deadly, especially for children and the elderly. Although E. coli bacteria infections are most common in developing countries, many recent outbreaks in Europe and Northern America have been attributed to a strain of E. coli bacteria which has been identified among the most common causes of diseases related to food safety. Accurate routine testing is crucial for outbreak prevention.
There are available techniques for detecting E. coli bacteria. The current techniques require time-consuming amplification of samples and the standard detection process of E. coli bacteria takes about 24 hours to obtain results from culturing methods. Although more recent detection techniques such as PCR (Polymerase Chain Reaction), ELISA (Enzyme Linked Immuno-Sorbent Assay) and IMS (Ion Mobility Spectrometry) offer a more rapid detection, an analysis time of several hours is still required. For the specific and rapid detection of such pathogens, bio-recognition elements such as antibodies, nucleic acids (DNA/RNA) and bacteriophages have widely been used for the specific capturing of the target bacteria. Their binding can be detected by fluorescence labeling methods or by label-free methods. Each of these recognition elements has its own advantages and disadvantages. For example, recognition based on nucleic acid, though offering high specificity, suffers from the inability to discriminate between viable and non-viable cells. For antibody-based recognition elements, the drawbacks are high manufacturing cost, lack of stability/repeatability in measurements and cross-binding to other bacteria which may result in false positives.